Supervisory control apparatus of the type here in question generally electrically monitor various operation parameters at an unmanned operating site. If a deviation in a desired range of parameters is noted, the apparatus conventionally generates alarms which are then transmitted to a central location. At the central location, there is usually a control center which contains equipment capable of displaying the existence of an alarm and/or various operating parameter levels on command. This control center is, as well, generally equipped with a control apparatus which can be manipulated by an operator to correct defects in or minimize the effects of malfunctions in the monitored equipment at the remote site. This form of operation has as its ultimate purpose the improvement of performance in an unmanned equipment site. In addition, the removal of the necessity for sending a repair crew or operating personnel to the remote site provides a major cost savings.
In conventional systems the central location is generally equipped with a computer having appropriate peripheral equipment and connected to the remote location, usually through leased telephone lines. Generally speaking, the equipment at the remote location is specifically programmed to operate in a given manner in response to various conditions and to produce corresponding signals. In order to effect a change in monitoring operations, the monitoring equipment at the remote site must be reprogrammed there, or, perhaps, changes in the programming of the remote equipment can be effected by means of the computer at the central location through the aforementioned telephone lines. As might be expected, the central control center must be manned at all times to ensure the proper operation of the system.
More recent developments in systems of this nature have permitted such supervisory monitor and control apparatus to use the telephone dial-up network and a standard push-button telephone to communicate with the remote site. The developments include the provision of voice synthesis equipment at the remote site to communicate information to the user, and the operator can use push-buttons on his telephone to produce dual tone, multi-frequency (DTMF) signals to enter various user access codes to set control switches and the like at the remote site. Again, however, programming of the monitoring and alarm equipment at the remote site must still be done at a central location using a computer found at that location. Consequently, in the prior art systems, despite the fact that the remote supervisory apparatus is accessible via a push-button telephone, if errors in operation should be noted, the apparatus cannot be reprogrammed from the push-button telephone to make the necessary corrections or changes.